A simulation device 20A has an operation terminal 21, a display section 22, a simulation section 23, and a unit shape data 24. The simulation section 23 is linked to an actual exposure device, in real time and execute a 3D simulation, following the operation of a respective control object unit 13 (control command). The control command is transferred from a device controller 12 to the control object unit 13, and also simultaneously to an simulation section 23. After receiving the control command, the simulation section 23 executes simulation, by operating the control object unit 13 as the control command commands.